Signaling apparatus



y 1932- H. o. HOLTE SIGNALING APPARATUS Filed April 8, 1925 INVENTORI #l-,@, M,

H4 ATTORNEY Patented May 17, 1932 UNITED STATES PATENT OFFICE HAROLD 0. ZH OLTE, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOE TO THE "UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA SIGNALING- APPARATUS Application filed A ril 8,

My invention relates to signaling apparatus, and particularly to apparatus for signaling between two points on a railway train, such, for example, as between the locomotive and the caboose of a freight train, or between the first locomotive and a second locomotive at the rear of the train. 7

I will describe one form and arrangement of signaling apparatus embodying my invention, and will then point out the novel features thereof in claims. i

The accompanying drawing is a view, partly diagrammatic, showing one form and arrangement of signaling apparatus embodying my invention. A u

'Referring to this drawing the apparatus comprises a transmitting mechanism designated as awhole by the reference character X, and a receiving mechanism designated as a whole by the reference character Y, both associated with the usual train brake pipe A extending throughout the length of the train and containing air under pressure. The

brake pipe A is provided, as usual, with branch pipes A, leading to the brake mechanism, etc., on each car. 1

The transmitting mechanism X comprises a chamber 1 connectedwith the brake pipe A and divided into an upper compartment 3 and a lower compartment 4: by means of a diaphragm or piston 2., The lower compartment 1 contains apparatus forvibratingthe diaphragm 2 which apparatus as here-shown comprises a circular .plate 6, rotatable about its center 7 and provided at its periphery with gear teeth meshing with a bevel pinion 6 The pinion (S ris rotated by a motor K which is supplied with current from a suitable source of energy such as a battery 10 through a circuit controller 9 which may be controlled in any desired manner. A link 8 has its upper end fastened t'odiaphragm 2, and the lower end of this link is constrained to move in a circularpath 'by fastening this end to a point on theplate 6 eccentric with respect to the center 7. It will be clear that 7 when circuit controller 9 is closed motor K will drive plate 6 and hence will vibrate diaphragm 2. Since the upper surface of diaphragm 2 is exposed to the air in the brake 1925. Serial No. 21,550.

pipe the vibrations of the diaphragm are transmitted through the air inthe brake pipe to the receiving apparatus Y in the form of pulsations, the frequency of which depends upon the speed of motor K. 1

A restricted passage 5 connects compartment 3 with compartment 4, to permit equalization ofthe air pressure on both sides of the diaphragm 2 when the brake pipe pressure is varied in manipulating the brakes.

The receiving mechanism comprises a chamber 11 divided into an upper compartmentp13 and a lower compartment 12 by a diaphragm let. These two compartments 13 and 12 areconnected by a restricted equalizing passage 15 for the same purpose as passage 5 in transmitting mechanism X. I

Since" the upper surface of diaphragm 14 is exposed to the air in the brake pipe, the pulsations impressed upon the brake pipe air cause this diaphragm to vibrate at the same frequency as the pulsations.

The compartment 12 contains a microphone P comprising, asusual, a cup 17 rigidly attached to the wall of chamber 11, but

insulated therefrom, and containing the usualcarbon'granules 18, and a button 1.6 attached to thefdiaphragm'1 1. A transformer D has 'a primary winding 19 con- 7 nected in series with a battery 20 and the microphone P. The. secondary 21 vof transformer D is connected with the winding-22 of a vibration relay E comprising a reed 2 1 vibrated by current in Winding22 and tuned to mechanical resonance at the frequency of the pulsations in brake pipe A. This reed co-acts with two fixed contacts 24 and 249, which are connected with the left hand and right hand terminals respectively of a battery 25. A transformer F has its primary winding v28 tuned to approximate resonance at the frequency of the pulsations, in the brake pipe by means of a condenser 27. The lower terminal of primary'28 is connected with reed 2 1, and the upper terminalofthis primary is connectedwith the midpoint of battery 25. A slowpick-uprelay His con- 7 nected, through a. rectifier G, with secondary 29 oftransformer F; 1 y V The relayl-I co 'trols'any suitable form of,

signal J, such as an electric horn, so that when the relay H is energized current is sup plied to signal J from battery 31 over front contact 30 of relay H.

The operation of the apparatus is as follows:

When circuit controller 9 is "closed, motor K is operated to impress pulsations of a given frequency upon the air in pipe A; These pulsations are transmitted to the receiving apparatus atY where diaphragm 14 is vibrated at the same iven fre uenc Micro- V phone P then operates to vary the resistance of the circuit through battery and a pula periodically reversing direct current the periodicity of which'is the same as that of the pulsations in pipe A." The alternating current supplied by secondary 29 of trans former F is then changed, by rectifier G, into a direct current which energizes relay Hand,

closing'front contact 30, operates signal J. Signal J is thereforeoperated as long as circuit controller 9 is closed."

It should be pointed (mum since relay H has slow pick-up characteristics, a single surge of energy will not close contact 30, but 'that continuousenergy mustbe supplied to "actuate signal J.

I I have found that if the pulsations impressedupon'the air in the brake pipe have "a wave length such that the effective resonant length'of any of the branch pipesA is approximately one quarter, three quarters, or

T fivequart'ers of one wave length, the branch will absorb a large amount of the energy of the pulsations and the attenuation along the brakepipe will be excessive. 'It is therefore desirable to choose a frequency for the pulsations such that the elfects'of this absorption phenomenon will be reduced to a minimum.

It is known also that the attenuation in a long. straight pipe increases about as the square root of the frequency. It is therefore undesirable to use higher frequencies. Consequently,l .preferto accomplish the signallength." By effective length ofa'branchpi'pe Ijmean' the total resonant length of 'the pipe including any cylinders,valves, or other deviceswhichmaybein'comimmication with mg by meansflof pulsations having lengthisless thanone fourth of one wave a frequency so. lowthat the effective length of the jbranch pipe having the: greatest effective the pipe. In ordinary use, with triple valves in lap or service positions, the effective lengths of these branch pipes, vary from two to seven feet,-vand so I choose pulsations of a ,can be used without excessive attenuation must be less than 11,000 dividedby 28, that is, less than 40 pulsations per second.

With frequencies of this order successful communication can be established between widely spaced points on a train with a minimum of expended power. a

One advantage of my invention is that since the secondary circuit of transformer'D and the primary circuit of transformer F, as well as the reed 24 of relay'E, are all tuned to resonance at the frequency of'the pulsations used, danger of interference from stray power sources or mechanical vibrationis reduced to a minimum. V It should also be particularly'noticed that since the reed 24 is tuned and controls ajlocal source of energy, the current supplied-to relay H will be substantially constant irrespective of the amplitude of the pulsations in the brake pipe air. 7 Although I have herein shown and described only one form and arrangement of signaling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without Since the velocity 'of transmission. 7

departing from thespirit and scope'of my invention. Having thus described my invention, what- I claim is: i

1. Apparatus for signaling between two points'on a train comprising, in'combination with the brake pipe having the nsual' branches, means for imposing upon theair in' such brake "pipe pulsations of a wave length more than four'times the longest effective length of a branch pipe.

2. Apparatustfor signaling between two points on a train comprising in combination with the brake pipe having the usual branches, meansfor impressing upon the air in said brake pipe pulsations of such frequency that the effective length of the branch pipe having the greatest effective length. is

less than one fourth of the wave length of said pulsations, and a signal controlled by said pulsations.

In testimony whereof I aflix my signature.

' HAROLD O. HOLTE. 

